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Commit 3a3d1a4e authored by Lee Jones's avatar Lee Jones Committed by Thierry Reding
Browse files

pwm: Add PWM capture support 



Supply a PWM capture callback op in order to pass back information
obtained by running analysis on a PWM signal. This would normally (at
least during testing) be called from the sysfs routines with a view to
printing out PWM capture data which has been encoded into a string.

Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
[thierry.reding@gmail.com: make capture data unsigned int for symmetry]
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 1a695a90

drivers/pwm/core.c

+27 −0
Original line number Diff line number Diff line
@@ -524,6 +524,33 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) 
}

EXPORT_SYMBOL_GPL(pwm_apply_state);



/**

 * pwm_capture() - capture and report a PWM signal

 * @pwm: PWM device

 * @result: structure to fill with capture result

 * @timeout: time to wait, in milliseconds, before giving up on capture

 *

 * Returns: 0 on success or a negative error code on failure.

 */

int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,

		unsigned long timeout)

{

	int err;



	if (!pwm || !pwm->chip->ops)

		return -EINVAL;



	if (!pwm->chip->ops->capture)

		return -ENOSYS;



	mutex_lock(&pwm_lock);

	err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout);

	mutex_unlock(&pwm_lock);



	return err;

}

EXPORT_SYMBOL_GPL(pwm_capture);



/**

 * pwm_adjust_config() - adjust the current PWM config to the PWM arguments

 * @pwm: PWM device

include/linux/pwm.h

+24 −0
Original line number Diff line number Diff line
@@ -5,7 +5,9 @@ 
#include <linux/mutex.h>

#include <linux/of.h>



struct pwm_capture;

struct seq_file;



struct pwm_chip;



/**
@@ -153,6 +155,7 @@ static inline void pwm_get_args(const struct pwm_device *pwm, 
 * @free: optional hook for freeing a PWM

 * @config: configure duty cycles and period length for this PWM

 * @set_polarity: configure the polarity of this PWM

 * @capture: capture and report PWM signal

 * @enable: enable PWM output toggling

 * @disable: disable PWM output toggling

 * @apply: atomically apply a new PWM config. The state argument
@@ -172,6 +175,8 @@ struct pwm_ops { 
		      int duty_ns, int period_ns);

	int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,

			    enum pwm_polarity polarity);

	int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,

		       struct pwm_capture *result, unsigned long timeout);

	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);

	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);

	int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
@@ -212,6 +217,16 @@ struct pwm_chip { 
	bool can_sleep;

};



/**

 * struct pwm_capture - PWM capture data

 * @period: period of the PWM signal (in nanoseconds)

 * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)

 */

struct pwm_capture {

	unsigned int period;

	unsigned int duty_cycle;

};



#if IS_ENABLED(CONFIG_PWM)

/* PWM user APIs */

struct pwm_device *pwm_request(int pwm_id, const char *label);
@@ -322,6 +337,8 @@ static inline void pwm_disable(struct pwm_device *pwm) 




/* PWM provider APIs */

int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,

		unsigned long timeout);

int pwm_set_chip_data(struct pwm_device *pwm, void *data);

void *pwm_get_chip_data(struct pwm_device *pwm);
@@ -373,6 +390,13 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns, 
	return -EINVAL;

}



static inline int pwm_capture(struct pwm_device *pwm,

			      struct pwm_capture *result,

			      unsigned long timeout)

{

	return -EINVAL;

}



static inline int pwm_set_polarity(struct pwm_device *pwm,

				   enum pwm_polarity polarity)

{